East coast of England, 1971. Harvard student Mason Clay is writing a thesis on a group of settlers who travelled to America from the remote Essex coastal village of Wicken-juxta-Mare 300 years ago. Clay plans to visit Wicken as part of his research, and who better assist him with all things Essex than Albert Campion?

But Wicken is already firmly on Campion's radar thanks to Dame Jocasta Upcott's luxury yacht found beached on a mudbank close to the village, its captain very stuck - and very dead - in the mud. Was it a bizarre accident or something more sinister? Agreeing to Dame Jocasta's request to recover her beloved pet pooch, Robespierre, Campion finds himself in Wicken, surrounded by suspicious locals and tales of witchcraft, and soon discovers its past is linked to a number of current disturbing events . . .